1. Field of the Invention
The invention relates to data packet transmission and, more particularly, to a method and apparatus for Wireless transmission of data packets between network nodes in a control network.
2. Description of the Related Art
During wireless communication between network nodes in a control network, for example, for controlling machines, data packets are transmitted via radio interfaces. Wireless communication for controlling machines requires, on the one hand, very low latencies and, on the other, very high data transmission reliability. It is also necessary for the control network to be able to co-exist with other wireless networks, particularly if the control network serves as a higher-level control network. In this case, the provision of high data transmission reliability represents a technical challenge because the majority of conventional measures used to increase reliability during data transmission increase latency. Industrial production plants with machines controlled by a control network constitute a difficult environment for wireless communication via radio interfaces. Production plants or industrial production cells with machines are associated with metal surfaces that interrupt or reflect the data transmission signals so that a relatively high level of electromagnetic noise is present. The reflecting metal surfaces result in multipath signal propagation.
The above-named problems mean conventional radio network technologies, such as Bluetooth or Institute of Electrical and Electronic Engineers (IEEE) standard 802.15.4 are not really suitable for control networks, i.e. in industrial production environments or factory automation.
Therefore, data transmission according to IEEE standard 802.15.4a was proposed in which data packets are transmitted in a wireless manner between network nodes of a control network. However, it has been found that data packet transmission according to IEEE standard 802.15.4 results in a high data packet loss rate. Here, the high packet loss rates are above all due to incorrectly recognized preambles in the headers of the data packets. This occurs in particular in receivers of network nodes, which work by energy detection.